1. Field of the Invention
The present invention relates generally to a system for removing environmentally harmful volatile containments from saturated or groundwater regions of the soil subsurface. More particularly, the present invention relates to an adjustable depth air sparging well which uses injected air to remove volatile containments from the saturated or groundwater regions of the soil subsurface.
2. Description of the Prior Art
Air sparging is a relatively recent and a very innovative technology that uses air injected under pressure to remove environmentally harmful volatile contaminants. Air sparging systems are capable of removing volatile contaminants such as gasoline, certain solvents and jet fuels from the groundwater region of the soil subsurface. In particular, air sparging systems are used to remove residual source contamination, clean up dissolved phase contamination, and contain a migrating contaminant plume.
Referring to FIG. 1, the major components of an air sparging system, designated generally by the reference numeral 18, (as shown in FIG. 1) consist of a permanently installed, vertical, single depth air sparge well 20, an air blower or compressor 22 which supplies air under pressure to sparge well 20 and monitoring sensors and equipment (not illustrated in FIG. 1). A screened bottom portion 24 of the air sparging system 20 is located below the contamination level 27. Air under pressure is injected through the screened bottom portion 24 of system 20 into the soil's saturated zone 28. This injected air strips the contaminants from a liquid phase to a vapor phase, and then transports the contaminants via air channels 30 to the soil's vadoze zone 32 for removal from the vadoze zone 32.
Referring to FIG. 2, clay soils and highly stratified layers, represented generally by the reference numeral 34, limit the effectiveness of air sparging systems 18 of the type illustrated in FIG. 1 by significantly decreasing uniform air distribution throughout soil's saturated zone 28. As shown in FIG. 2, the air channels 36 are not uniformly distributed throughout the soil's saturated zone 28, resulting in areas of the saturated zone 28 from which volatile contaminants can not be removed. In particular, injected air will not penetrate the clay soils and highly stratified layers 34, which leaves the volatile contaminants in the region 29 above the clay soils and highly stratified layers 34 in the saturated zone.
Nested air sparge wells have been used as an alternative to vertical sparge wells to remove volatile contaminants when the soil is highly stratified. Nested air sparge wells are costly due to the drilling cost associated with these wells.
A second alternative is to place vertical sparge wells adjacent to one another for uniform injection of air within the soil which will generally result in significant cost increases, while not assuring complete success at stratified sites within a contaminated saturated zone.
In addition, once nested or adjacent air sparge wells are installed, there is currently no method to adjust the sparging depth to assure that volatile contaminates are completely removed from contaminated saturated zones of the type illustrated in FIG. 2.
Accordingly, there is a need for an adjustable depth air sparge well which will allow for the removal of environmentally harmful volatile contaminants from saturated or groundwater regions of the soil, especially where stratification is a significant problem. In addition, there is a need to provide an adjustable depth air sparge well which is relatively simple in design and provides for significant operational cost reduction over air sparging systems currently in use.